[Xen-bugs] A potential Xen bug - Fwd: Re: [Openswan Users] klips_error:ipsec_xmit_encap_once: tried to skb_put 20, 16 available. This should never happen, please report.

[Danilo Godec <danilo.godec@xxxxxxxxx>]

I'm having some weird networking issue which seem to happen only on a Xen VM.  Initially I suspected OpenSwan but one of the developers suggested it might be a Xen (networking) issue.

Bellow is the correspondence with Mr. Paul Wouters:

============

-------- Original Message --------

Subject:	Re: [Openswan Users] klips_error:ipsec_xmit_encap_once: tried to skb_put 20, 16 available. This should never happen, please report.
Date:	Sat, 2 Oct 2010 12:24:54 -0400 (EDT)
From:	Paul Wouters <paul@xxxxxxxxxxxxx>
To:	Danilo Godec <danilo.godec@xxxxxxxxx>
CC:	users@xxxxxxxxxxxxxxxxxx

On Sat, 2 Oct 2010, Danilo Godec wrote:

> I have a server running OpenSwan 2.6.29, using MAST stack. The server
> has three Xen VM's and currently 4 active LAN's behind. There is not a
> lot of traffic yet, as the building is not quite finished...
>
> If I connect to a VM and run a simple 'ls -lR /' it will sometimes get
> 'stuck'. At that moment, a lot of these messages appear on the IPSEC server:
>
>> Oct  2 14:04:34 lmqxen1 kernel: [59061.763064]
>> klips_error:ipsec_xmit_encap_once: tried to skb_put 21, 17 available.
>> This should never happen, please report.

Are you running tight on memory?

> I also see these messages when 'cfagent' (a part of 'cfengine') on a VM
> copies files from the server and gets stuck...

Yeah, this does not seem to be an openswan bug. The code in question is:
(one instance of it):

        /* Set the data pointer */
        skb_reserve(n,skb->data-skb->head+headroom);
        /* Set the tail pointer and length */
        if(skb_tailroom(n) < skb->len) {
                printk(KERN_WARNING "klips_error:skb_copy_expand: "
                       "tried to skb_put %ld, %d available.  This should never happen, please report.\n",
                       (unsigned long int)skb->len,
                       skb_tailroom(n));
                ipsec_kfree_skb(n);
                return NULL;
        }

I would check with the xen people to see what might be going on.

Paul


============

The server runs OpenSuSE 11.2 (x86_64), has 4GB of RAM, each of three VM's allocates 512MB. Xen version is 3.4.1, I'm using bridged networking. Each VM has it's own bridge and it servers as a router for the subnet.

I couldn't see any error messages in Xen logs...

Any ideas?

   Regards, Danilo

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